20812745 has 4 divisors (see below), whose sum is σ = 24975300. Its totient is φ = 16650192.

The previous prime is 20812721. The next prime is 20812747. The reversal of 20812745 is 54721802.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 54721802 = 2 ⋅27360901.

It can be written as a sum of positive squares in 2 ways, for example, as 5004169 + 15808576 = 2237^2 + 3976^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20812745 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (20812747) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2081270 + ... + 2081279.

It is an arithmetic number, because the mean of its divisors is an integer number (6243825).

Almost surely, 2^20812745 is an apocalyptic number.

It is an amenable number.

20812745 is a deficient number, since it is larger than the sum of its proper divisors (4162555).

20812745 is an equidigital number, since it uses as much as digits as its factorization.

20812745 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4162554.

The product of its (nonzero) digits is 4480, while the sum is 29.

The square root of 20812745 is about 4562.0987494792. The cubic root of 20812745 is about 275.0699326278.

The spelling of 20812745 in words is "twenty million, eight hundred twelve thousand, seven hundred forty-five".